Hydraulic balance for multistage pumps



Feb. 10, 1925. 1525,73?

A. HOLLANDER HYDRAULIC BALANCE FOR MULTISTAGE PUMPS Filed March 27, 1924 IN VEN TOR.

ATTORNEYS Patented Feb. 1d, 1925.

uurrsn Parent res.

HYDRAULIC BALANCE FOR M'ULTISTAGE PUMPS.

Application filed March 27, 1924:. Serial No. 702,243.

To all whom it may concern:

Be it known that I, ALADAR HOLLANDER, a citizen of the United States. and resident of the city of Berkeley, county of Alameda,

State otCalifornia, have invented new and useful Improvements in Hydraulic Balances for Multistage Pumps, of which the follow} ing is a specification.

My invention has for its object the counter balancing of end thrusts in the rotating element of a multi-stage centrifugal pump by establishing a differential pressure toward the suction end of one of the runners and opposing said pressure by a variable pressure compartment adjacent said suction end.

These objects I attain by introducing structural inequalities whereby an overbalancing or differential thrust is created, in opposition to the direction of the water entering one of the runners and then oppose this established thrust by an automatically controlled pressure chamber between the in let side oh the last na-med runner and a stationary portion of the casing.

Other objects will appear from the drawing and specifications which follow.

By referring to the accompanying drawing my invention will be made clear.

The figure shows a vertical cross section through a multi-stage centrifugal pump to which my invention has been applied.

The numeral 1 indicates the inlet elbow of such a pump attached to a stationary portion of the casing 2. The casing cover is shown at 3 carrying the bearing 4 and discharge outlet 5. At 6 is a shaft adapted to rotate in the gland 7 and bearing 4 and carrying the low pressure runner 8 and high pressure runner 9, these runners being coupledltogether and provided with any suitable key at 10.

At 11 is a diaphragm or plate dividing the low pressure volute 12 from the big pressure volute 13, this plate being fixed to the annular opening in the casing by screws at 14. At .15 and 16 are rings on the stationary casing and runner 9 respectivel and forming a running joint through 60 whic the leakage under any given diflerential pressure is substantially constant; and at 17, 18 are flanges on the stationary element and runner 9 respectively forming a variable passageway 19 through which any means in the shaft as indicated fluid in 20 finds egress into the suction side of the runner 9.

In the example here chosen the :followingv assumptions are made:

a indicates the area of shaft 6;

Z) the area of the running joint at the suction inlets of the runners.

0 indicates the area of the runners.

- 0! indicates the area of the running joint circle between the runners.

e indicates the area of the running joint circle at the inlet of the variable pressure chamber :20. Y

The arrows f and 9 indicate the direction of axial forces and assuming 100 pounds per square inch delivery pressure, pounds per square inch intermediate pressure, and zero inlet pressure at the runner 8 and as suming also- (1 equals 10 square inch.

5 equals .30 square inch.

0 equals 50 square inch.

d equals 15 square inch.

6 equals 42 square inch.

In practicing my invention the first step is to insure or create a, difierential thrust in one direction to-wit, toward the suction inlet of one of the runners and in opposition to the force to be exerted by the variable pressure chamber, regardless of any inequalities in the design and constructions of the parts and, exclusive of the variable pressure chamber. In the case here chosen such a force is first established in the direc tion of the arrow g by making the hub (13 larger than it. And without considering for a moment the effect of the chamber 20 we would have:

(b--a) 0+(cb) 50+(0-d) 100 g:1000+3500::4500 (H) 50+ (c-e) XlOO-l- (0d) X50 2 f is therefore to be supplemented by 1000 pounds or contributed from the variable ressure chamber 20 to compensate for the differential of 1000 or excess in the force 9'.

My counter-balanced chamber 20 will now modify the above conditions as follows: It the force due to the pressure in chamber 20 becomes greater than that necessary to counter-balance the rotating element the latter will move to increase the passageway 19, allowing fluid to escape therefrom and therefore reducing the counter-balancing force. If the pressure in 20 becomes less than that necessary to counterbalance the differential force the movement of the rotating element will be in the opposite direction reducing passage 19 and increasing the fluid pressure in chamber 20. If the pressure in chamber 20 rises above or falls below the pressure necessary to efiect a counter-balance the rotating element will move to readjust the discharge passage 19.

In the example above the maximum pressure in chamber 20 will be 100 pounds per square inch, equal to the pressure in the V0- lute 13 when assage 19 is closed and the minimum will l ie 50 pounds per square inch when the passage 19 is wide open and pressure is equalized with the suction inlet pressure in runner 9, which is of course equal to the pressure in the volute 12.

The correct counter-balance to effect equilibrium in the running conditions, must therefore be found between 50 and 100 pounds as the unit pressure in chamber 20.

The area ex sed to pressure in chamber 20 is (pr-b :(42 30):12 inches and the differential force to be countor-balanced is 1000 pounds; therefore we pounds er square inch will be the pressure in chain r 20 when the passage 19 has been automatically adjusted to the condition of running balance of the rotating element.

the

square If the force is larger than 1000 pounds the rotating element will move to the right increasing the passage 19.

In the above example, casting inequalities and leakages have been ignored and in practice these will introduce a variation from the figures given and are one of the causes that make necessary a variable counter-balance. This my invention supplies in this type of pump with the maximum eficiency and maintenance and simplest construction.

I claim:

1. In a fluid premure apparatus a plurality of impellers mounted on a shaft, said impellers arranged with oppositely directed suction passages and each impeller enclosed in a pressure compartment, said impellers having different areas exposed to axially directed pressure whereby a thrust is established in an axial direction toward the suction passage of one of the impelleis and a variable pressure chamber on the suction passage side of and between the last named runner and the corresponding oon'ipartment wall, a passage of relatively constant area from the corresponding pressure compartment to the chamber and a variably throttled passage from the chamber to the last named suction passage.

2. Fluid pressure apparatus as set forth in claim 1 wherein there is a hub and a running joint between the runners of greater area than the shaft diameter in the suction passages.

- ALADAR HOLLANDER. 

